(a) Field of the Invention
This invention relates to N-alkyl-N'-[5-(pyridinyl)-2-pyridinyl]ureas, their use as cardiotonic agents, and their preparation.
(b) Description of the Prior Art
Lesher, Opalka and Page [U.S. Pat. No. 4,297,360, issued Oct. 27, 1981] show, inter alia, as cardiotonic agents and as intermediates, 5-(pyridinyl)pyridin-2-amines, e.g., 5-(4-pyridinyl)pyridin-2-amine, alternatively named [3,4'-bipyridin]-6-amine, which are used herein as intermediates.
Lesher, Opalka and Page [U.S. Pat. No. 4,276,293, issued June 30, 1981] show, inter alia, as intermediates, 5-(pyridinyl)pyridin-2-amines, e.g., 5-(4-pyridinyl)pyridin-2-amine.
D. A. Inoyatova et al. [Chem. Absts. 74, 125,360b (1971); Tr. Samarkand. Gos. Univ. 1969, No. 167, 173-4 (Russ.) From Ref. Zh., Khim 1970, Abstr. No. 5Zh482] report the amination of 3,3'-bipyridine and subsequent thin-layer chromatography using diethyl ether to produce 6-amino-3,3'-bipyridine, alternatively named 5-(3-pyridinyl)pyridin-2-amine.
Lesher and Gruett [British Pat. No. 1,322,318, published July 4, 1973] show as intermediates for preparing antibacterially active 1-alkyl-1,4-dihydro-4-oxo-7-PY-1,8-naphthyridine-3-carboxylic acids and esters (where PY is 4- or 3-pyridinyl or 4- or 3-pyridinyl having one or two lower-alkyl substitutents) 2-amino-6-(4- or 3-pyridinyl)pyridine, alternatively named 6-(4- or 3-pyridinyl)pyridin-2-amines.
Lesher and Page [U.S. Pat. No. 4,317,827, issued Mar. 2, 1982] show inter alia, N-[4-(4-pyridinyl)phenyl]-urea, useful as a cardiotonic, and its preparation by reacting 4-(4-pyridinyl)benzeneamine with potassium cyanate in warm aqueous acetic acid solution.
Boehmer [C.A. 30, 5950.sup.4 (1936); Rec. trav. chim. 55, 379-91 (1936)] shows the reaction of pyridin-2-amine with lower-alkyl isocyanates to produce N-alkyl-N'-(2-pyridinyl)ureas where alkyl is methyl, n-propyl, isopropyl, n-butyl and isobutyl.